Over the years there have been a number of procedures and types of trim elements used to install windows into vehicles so that the window would be both securely fastened in place and at the same time fully sealed to prevent water leakage. These procedures have evolved into one employing trim elements that fit around the periphery of the window and an adhesive type sealing compound, in order to help effect a very tight and permanent seal. While procedures vary, the adhesive or mastik compound is either placed in the body cavity designed to receive the window or as is more usually the case directly onto the window itself. The trim elements used hopefully to help align the window within the body cavity, do become part of the means securing the window in place. Traditionally, the body cavity is provided with a flange or some member extending around the body cavity onto which at least one trim element can be fastened by using a wire embedded in the trim and bent to grip the flange. A chamber is formed between the body cavity, the window and the trim elements and the sealing compound will hopefully flow throughout that cavity and through the wire structure part of which is usually in the form of an open grid.
When the trim elements and adhesive are properly positioned and the window is pressed into the body cavity, the adhesive compound will flow throughout the chamber and through the exposed open grid of wire and will bond together the trim structures and body flange exposed therein to produce a water tight seal around the marginal edge of the window.
It is of course desirable, if not necessary, to control the flow path of this adhesive material as the window is being pressed into the body cavity and the adhesives flowing. Toward that end the trim elements employed include some means to prevent the adhesive compound from flowing out of the chamber formed between the window and the body cavity, especially out onto the glass and the exterior of the trim.
One known trim structure in current use is shown in FIGS. 1 and 2. The molding in this known structure is comprised of a plurality of separate elements. These include a continuous elongated trim member secured to a flange within the body cavity in which the window will be received. This trim member, in part, serves to define part of the chamber on one side of the marginal edge of the window. A separate dam member, secured to the window by a separate process prior to the window's installation, cooperates with the interior of the trim member to prevent adhesive material from flowing onto the window during installation. The structure also includes an exterior trim, referred to as Christmas tree trim, which has an interior end structure exposed within the chamber formed between the window and the body cavity.
When the windshield is installed, the adhesive is forced throughout the void or chamber between the marginal edge of the window, the body cavity and the trim elements and flows into and around the exposed portions of each trim element and also onto the windshield and portions of the body cavity which are likewise exposed within the chamber. The function of the separate dam member is to prevent the flowing adhesive from getting out of the chamber and onto the exterior of the trim member or onto the glass beyond the trim.
The typical assembly procedure for this known prior art device is initiated by precoating the body flange with an urethane primer and thereafter mounting the windshield trim onto the flange provided on the vehicle body. The separate dam is adhesively bonded to the windshield at what is hoped to be the correct predetermined distance away from the marginal edge of the window. After the adhesive material is applied either to the vehicle body or to the marginal edge of the window, the latter being the preferred practice it will be located between the window's edge and the separate dam previously applied. Thereafter, with the separate dam in place and the adhesive having been applied, the window is pushed into the body cavity on which the primary trim member has already been positioned. When the window is in place, a gap will remain between a portion of the vehicle body and the edges of the window and the Christmas tree trim material is forced into that opening to close it. The inner end of that Christmas tree trim will contact the adhesive flowing throughout the chamber between the glass and the body cavity. The separate dam member should prevent or limit flow of adhesive therepast but this will only occur if its placement on the interior surface of the windshield was correctly accomplished.
The windshield trim is reinforced with a wire structure that is folded back on itself so as to form a U-shaped clip which will hold the trim on the body cavity flange. It is preferred that the reinforcing material exposed above the flange have an opened structure so that the adhesive can flow through that open network of reinforcing material, usually wire. Likewise when the Christmas tree trim itself is pushed into the opening between the vehicle's body and the edge of the window, the leading portion of that trim member will also be pushed into the adhesive material. Thus, the adhesive will have flowed not only through the cavity formed between the window and the car body, but also through or around the various trims that enclose the exterior and interior marginal edge portions of the windshield.
Problems exist, however, in achieving the proper placement of the separate dam on the window and unless that is accurately done, problems can develop. For instance, the dam member can be positioned closer or further away from the marginal edge of the window than is desired. If the dam member is closer to the window's edge, its bottom sealing edge will engage the open reinforcing member and also the volume of the chamber for containing adhesive will be smaller. When the window is pushed into place the adhesive will have greater pressure applied to it and some may flow beneath the dam, through the open reinforcing network and possibly out beyond the main trim member.
If the dam is further away from the edge a much larger void is formed between the marginal edge of the windshield and the vehicle body so that the adhesive will not be fully forced throughout that chamber. Further, the dam itself can be exposed above the main trim and become a visual part of the interior trim along the window edge which is not desirable. By having the dam sit away from the edge a further degree, the glass will sit higher than required and will not be flush with the vehicle body portion designed to receive it; the void or chamber becomes even larger and the adhesive may not provide the same water tight seal that would otherwise be achievable. Accordingly, the exact placement of that separate dam on the window is critical to achieving both a water tight and visually attractive seal.
Also, even if the dam is positioned correctly on the window, the window may be misaligned when placed in the body cavity. Thus, the dam could, in part, become positioned interiorly of the main trim member making the dam totally ineffective in that area.
Additionally, the use of the separate dam required not only additional material, but more importantly requires the use of an additional processing step in the installation of the window, thus, adding two separate additional cost factors to the price of the vehicle itself while at the same time provide a joining technique that requires additional time and effort.